/*
 * md5.c
 *
 *  Created on: 2015-2-3
 *      Author: YanJun
 */

#include <memory.h>
#include "md5.h"

static unsigned char PADDING[] = { 0x80, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
		0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
		0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };

void MD5Init(MD5_CTX *context) {
	context->count[0] = 0;
	context->count[1] = 0;
	context->state[0] = 0x67452302;
	context->state[1] = 0xEFCDAB89;
	context->state[2] = 0x98BADCFE;
	context->state[3] = 0x10325476;
}

void MD5Update(MD5_CTX *context, unsigned char *input, unsigned int inputlen)
{
	unsigned int i = 0, index = 0, partlen = 0;
	index = (context->count[0] >> 3) & 0x3F;
	partlen = 64 - index;
	context->count[0] += inputlen << 3;
	if (context->count[0] < (inputlen << 3))
		context->count[1]++;
	context->count[1] += inputlen >> 29;

	if (inputlen >= partlen) {
		memcpy(&context->buffer[index], input, partlen);
		MD5Transform(context->state, context->buffer);
		for (i = partlen; i + 64 <= inputlen; i += 64)
			MD5Transform(context->state, &input[i]);
		index = 0;
	} else {
		i = 0;
	}
	memcpy(&context->buffer[index], &input[i], inputlen - i);
}

void MD5Final(MD5_CTX *context, unsigned char digest[16])
{
	unsigned int index = 0, padlen = 0;
	unsigned char bits[8];
	index = (context->count[0] >> 3) & 0x3F;
	padlen = (index < 56) ? (56 - index) : (120 - index);
	MD5Encode(bits, context->count, 8);
	MD5Update(context, PADDING, padlen);
	MD5Update(context, bits, 8);
	MD5Encode(digest, context->state, 16);
}

void MD5Encode(unsigned char *output, unsigned int *input, unsigned int len)
{
	unsigned int i = 0, j = 0;
	while (j < len) {
		output[j] = input[i] & 0xFF;
		output[j + 1] = (input[i] >> 8) & 0xFF;
		output[j + 2] = (input[i] >> 16) & 0xFF;
		output[j + 3] = (input[i] >> 24) & 0xFF;
		i++;
		j += 4;
	}
}

void MD5Decode(unsigned int *output, unsigned char *input, unsigned int len)
{
	unsigned int i = 0, j = 0;
	while (j < len) {
		output[i] = (input[j]) | (input[j + 1] << 8) | (input[j + 2] << 16)
				| (input[j + 3] << 24);
		i++;
		j += 4;
	}
}

void MD5Transform(unsigned int state[4], unsigned char block[64])
{
	unsigned int a = state[0];
	unsigned int b = state[1];
	unsigned int c = state[2];
	unsigned int d = state[3];
	unsigned int x[64];
	MD5Decode(x, block, 64);
	FF(a, b, c, d, x[ 0], 7, 0xd76aa478);
	/* 1 */
	FF(d, a, b, c, x[ 1], 12, 0xe8c7b756);
	/* 2 */
	FF(c, d, a, b, x[ 2], 17, 0x242070db);
	/* 3 */
	FF(b, c, d, a, x[ 3], 22, 0xc1bdceee);
	/* 4 */
	FF(a, b, c, d, x[ 4], 7, 0xf57c0faf);
	/* 5 */
	FF(d, a, b, c, x[ 5], 12, 0x4787c62a);
	/* 6 */
	FF(c, d, a, b, x[ 6], 17, 0xa8304613);
	/* 7 */
	FF(b, c, d, a, x[ 7], 22, 0xfd469501);
	/* 8 */
	FF(a, b, c, d, x[ 8], 7, 0x698098d8);
	/* 9 */
	FF(d, a, b, c, x[ 9], 12, 0x8b44f7af);
	/* 10 */
	FF(c, d, a, b, x[10], 17, 0xffff5bb1);
	/* 11 */
	FF(b, c, d, a, x[11], 22, 0x895cd7be);
	/* 12 */
	FF(a, b, c, d, x[12], 7, 0x6b901122);
	/* 13 */
	FF(d, a, b, c, x[13], 12, 0xfd987193);
	/* 14 */
	FF(c, d, a, b, x[14], 17, 0xa679438e);
	/* 15 */
	FF(b, c, d, a, x[15], 22, 0x49b40821);
	/* 16 */

	/* Round 2 */
	GG(a, b, c, d, x[ 1], 5, 0xf61e2562);
	/* 17 */
	GG(d, a, b, c, x[ 6], 9, 0xc040b340);
	/* 18 */
	GG(c, d, a, b, x[11], 14, 0x265e5a51);
	/* 19 */
	GG(b, c, d, a, x[ 0], 20, 0xe9b6c7aa);
	/* 20 */
	GG(a, b, c, d, x[ 5], 5, 0xd62f105d);
	/* 21 */
	GG(d, a, b, c, x[10], 9, 0x2441453);
	/* 22 */
	GG(c, d, a, b, x[15], 14, 0xd8a1e681);
	/* 23 */
	GG(b, c, d, a, x[ 4], 20, 0xe7d3fbc8);
	/* 24 */
	GG(a, b, c, d, x[ 9], 5, 0x21e1cde6);
	/* 25 */
	GG(d, a, b, c, x[14], 9, 0xc33707d6);
	/* 26 */
	GG(c, d, a, b, x[ 3], 14, 0xf4d50d87);
	/* 27 */
	GG(b, c, d, a, x[ 8], 20, 0x455a14ed);
	/* 28 */
	GG(a, b, c, d, x[13], 5, 0xa9e3e905);
	/* 29 */
	GG(d, a, b, c, x[ 2], 9, 0xfcefa3f8);
	/* 30 */
	GG(c, d, a, b, x[ 7], 14, 0x676f02d9);
	/* 31 */
	GG(b, c, d, a, x[12], 20, 0x8d2a4c8a);
	/* 32 */

	/* Round 3 */
	HH(a, b, c, d, x[ 5], 4, 0xfffa3942);
	/* 33 */
	HH(d, a, b, c, x[ 8], 11, 0x8771f681);
	/* 34 */
	HH(c, d, a, b, x[11], 16, 0x6d9d6122);
	/* 35 */
	HH(b, c, d, a, x[14], 23, 0xfde5380c);
	/* 36 */
	HH(a, b, c, d, x[ 1], 4, 0xa4beea44);
	/* 37 */
	HH(d, a, b, c, x[ 4], 11, 0x4bdecfa9);
	/* 38 */
	HH(c, d, a, b, x[ 7], 16, 0xf6bb4b60);
	/* 39 */
	HH(b, c, d, a, x[10], 23, 0xbebfbc70);
	/* 40 */
	HH(a, b, c, d, x[13], 4, 0x289b7ec6);
	/* 41 */
	HH(d, a, b, c, x[ 0], 11, 0xeaa127fa);
	/* 42 */
	HH(c, d, a, b, x[ 3], 16, 0xd4ef3085);
	/* 43 */
	HH(b, c, d, a, x[ 6], 23, 0x4881d05);
	/* 44 */
	HH(a, b, c, d, x[ 9], 4, 0xd9d4d039);
	/* 45 */
	HH(d, a, b, c, x[12], 11, 0xe6db99e5);
	/* 46 */
	HH(c, d, a, b, x[15], 16, 0x1fa27cf8);
	/* 47 */
	HH(b, c, d, a, x[ 2], 23, 0xc4ac5665);
	/* 48 */

	/* Round 4 */
	II(a, b, c, d, x[ 0], 6, 0xf4292244);
	/* 49 */
	II(d, a, b, c, x[ 7], 10, 0x432aff97);
	/* 50 */
	II(c, d, a, b, x[14], 15, 0xab9423a7);
	/* 51 */
	II(b, c, d, a, x[ 5], 21, 0xfc93a039);
	/* 52 */
	II(a, b, c, d, x[12], 6, 0x655b59c3);
	/* 53 */
	II(d, a, b, c, x[ 3], 10, 0x8f0ccc92);
	/* 54 */
	II(c, d, a, b, x[10], 15, 0xffeff47d);
	/* 55 */
	II(b, c, d, a, x[ 1], 21, 0x85845dd1);
	/* 56 */
	II(a, b, c, d, x[ 8], 6, 0x6fa87e4f);
	/* 57 */
	II(d, a, b, c, x[15], 10, 0xfe2ce6e0);
	/* 58 */
	II(c, d, a, b, x[ 6], 15, 0xa3014314);
	/* 59 */
	II(b, c, d, a, x[13], 21, 0x4e0811a1);
	/* 60 */
	II(a, b, c, d, x[ 4], 6, 0xf7537e82);
	/* 61 */
	II(d, a, b, c, x[11], 10, 0xbd3af235);
	/* 62 */
	II(c, d, a, b, x[ 2], 15, 0x2ad7d2bb);
	/* 63 */
	II(b, c, d, a, x[ 9], 21, 0xeb86d391);
	/* 64 */
	state[0] += a;
	state[1] += b;
	state[2] += c;
	state[3] += d;
}
